✅ Answer: Consider the following narrations:

1 عَنِ الْفَضْلِ بْنِ شَاذَانَ عَنِ الرِّضَا فِی کِتَابِهِ إِلَی الْمَأْمُونِ وَ التَّکْبِیرُ فِی الْعِیدَیْنِ وَاجِبٌ إِلَی أَنْ قَالَ وَ فِی الْأَضْحَی فِی دُبُرِ عَشْرِ صَلَوَاتٍ یُبْدَأُ بِهِ مِنْ صَلَاةِ الظُّهْرِ یَوْمَ النَّحْرِ- وَ بِمِنًی فِی دُبُرِ خَمْسَ عَشْرَةَ صَلَاةً

📚 Uyun Akhbar al-Reza, Vol. 2, p. 125

Imam Reza (peace be upon him) wrote to Ma’mun: Takbir is obligatory for Eid al-Fitr and Eid al-Adha ... and he continued until he said: For Eid al-Adha, it is after ten prayers starting from the noon prayer on the day of Eid al-Adha, and in Mina, it is after 15 prayers!

2 عَنْ عَمَّارٍ عَنْ أَبِی عَبْدِ اللَّه قَالَ: سَأَلْتُهُ عَنِ التَّکْبِیرِ فَقَالَ وَاجِبٌ فِی دُبُرِ کُلِّ صَلَاةِ فَرِیضَةٍ أَوْ نَافِلَةٍ أَیَّامَ التَّشْرِیقِ

📚 Al-Tahdhib, Vol. 5, p. 270

Ammar says: I asked Imam Sadiq (peace be upon him) about Takbir; he said: It is obligatory after every obligatory or supererogatory prayer during the days of Tashriq!

3 عَنْ زُرَارَةَ قَالَ: قُلْتُ لِأَبِی عَبْدِ اللَّه التَّکْبِیرُ فِی أَیَّامِ التَّشْرِیقِ فِی دُبُرِ الصَّلَوَاتِ فَقَالَ التَّکْبِیرُ بِمِنًی فِی دُبُرِ خَمْسَ عَشْرَةَ صَلَاةً وَ فِی سَائِرِ الْأَمْصَارِ فِی دُبُرِ عَشْرِ صَلَوَاتٍ وَ أَوَّلُ التَّکْبِیرِ فِی دُبُرِ صَلَاةِ الظُّهْرِ یَوْمَ النَّحْرِ- تَقُولُ فِیهِ

اللَّهُ أَکْبَرُ اللَّهُ أَکْبَرُ لَا إِلَهَ إِلَّا اللَّهُ وَ اللَّهُ أَکْبَرُ اللَّهُ أَکْبَرُ وَ لِلَّهِ الْحَمْدُ اللَّهُ أَکْبَرُ عَلَی مَا هَدَانَا اللَّهُ أَکْبَرُ عَلَی مَا رَزَقَنَا مِنْ بَهِیمَةِ الْأَنْعَامِ

📚 Al-Kafi, Vol. 4, p. 516

Zurara says: I asked Imam Sadiq (peace be upon him): How is the Takbir after prayers during the days of Tashriq? He said: In Mina, it is after 15 prayers, and in other cities, it is after ten prayers, and the first Takbir is after the noon prayer on the day of Eid al-Adha, and it is said as follows:

اللَّهُ أَکْبَرُ اللَّهُ أَکْبَرُ لَا إِلَهَ إِلَّا اللَّهُ وَ اللَّهُ أَکْبَرُ اللَّهُ أَکْبَرُ وَ لِلَّهِ الْحَمْدُ اللَّهُ أَکْبَرُ عَلَی مَا هَدَانَا اللَّهُ أَکْبَرُ عَلَی مَا رَزَقَنَا مِنْ بَهِیمَةِ الْأَنْعَامِ

4 عَنْ عَلِیِّ بْنِ جَعْفَرٍ عَنْ أَخِیهِ مُوسَی بْنِ جَعْفَرٍ قَالَ: سَأَلْتُهُ عَنِ النِّسَاءِ هَلْ عَلَیْهِنَّ التَّکْبِیرُ أَیَّامَ التَّشْرِیقِ- قَالَ نَعَمْ وَ لَا یَجْهَرْنَ

📚 Al-Tahdhib, Vol. 5, p. 481

Ali ibn Ja’far says: I asked Musa ibn Ja’far (peace be upon him) about women, whether they are required to say Takbir during the days of Tashriq? He said: Yes, but they do not say it loudly or openly!

5 عَنْ حَفْصِ بْنِ غِیَاثٍ عَنْ جَعْفَرٍعَنْ أَبِیهِ عَنْ عَلِیٍّ قَالَ: عَلَی الرِّجَالِ وَ النِّسَاءِ أَنْ یُکَبِّرُوا أَیَّامَ التَّشْرِیقِ فِی دُبُرِ الصَّلَوَاتِ وَ عَلَی مَنْ صَلَّی وَحْدَهُ وَ عَلَی مَنْ صَلَّی تَطَوُّعاً.

📚 Al-Tahdhib, Vol. 3, p. 289

Imam Ali (peace be upon him) said: It is upon men and women to say Takbir after prayers during the days of Tashriq, whether they pray individually or perform supererogatory prayers!

6 عَنْ عَمَّارٍ السَّابَاطِیِّ قَالَ: سَأَلْتُ أَبَا عَبْدِ اللَّهِ عَنْ رَجُلٍ یَنْسَی أَنْ یُکَبِّر فِی أَیَّامِ التَّشْرِیقِ- قَالَ إِنْ نَسِیَ حَتَّی قَامَ مِنْ مَوْضِعِهِ فَلَا شَیْ ءَ عَلَیْه

📚 Al-Tahdhib, Vol. 5, p. 487

Ammar says: I asked Imam Sadiq (peace be upon him) about someone who forgets to say Takbir during the days of Tashriq; he said: If they forget until they rise from their place, there is no obligation upon them!

7 عَنْ مُحَمَّدِ بْنِ مُسْلِمٍ عَنْ أَحَدِهِمَا قَالَ: سَأَلْتُهُ عَنِ التَّکْبِیرِ بَعْدَ کُلِّ صَلَاةٍ فَقَالَ کَمْ شِئْتَ إِنَّهُ لَیْسَ شَیْءٌ مُوَقَّتٌ یَعْنِی فِی الْکَلَامِ.

📚 Al-Kafi, Vol. 4, p. 517

Muhammad ibn Muslim says: I asked Imam Baqir or Imam Sadiq (peace be upon them both) about Takbir after prayers; he said: As many times as you wish! There is no limit in the words! (meaning you say it as many times as you want)

✅ The days of Tashriq refer to the three days following Eid al-Adha.

اللَّهُمَّ صَلِّ عَلَی مُحَمَّدٍ وَ آلِ مُحَمَّدٍ وَ عَجِّلْ لِوَلِیِّکَ الْفَرَجَ وَ الْعَافِیَةَ وَ النَّصْرَ